Draw 1) a context data flow diagram and 2) a level-0 diagram that shows the appropriate details for the point of sales system described below: Self-checkout system at Big Joes Supermarket uses a scanner to read universal product codes (UPC). When a customer scans a product, the system reads the code (i.e., barcode) of the product and retrieves product information based on data stored in a product file. The system displays the product summary to the customer. When the customer provides payment information, the system verifies the payment information by connecting to an external credit/banking verification system. Purchases made are stored in a file to be used in printing the receipt. After the purchase has been made a receipt is produced and given to the customer.